This invention relates to a device for the storage of hydrogen by use of an alloy capable of storing hydrogen therein.
Hydrogen, as an energy source which promises to take the place of fossil fuels such petroleum and coal which are destined to be exhausted sooner or later, has been attracting increasing attention.
Methods proposed to date for the storage of hydrogen include (A) a method for storing hydrogen in its gaseous form, (B) a method for storing hydrogen in its liquefied form, and (C) a method for storing hydrogen as metal hydride by use of an alloy.
The method (A), because of the necessity for handling hydrogen under a very high pressure exceeding 150 atmospheres, cannot necessarily be called an efficient approach and, to make the matter worse, proves deficient in safety. The method (B) has the disadvantage that the production of liquefied hydrogen requires supply of hydrogen of extremely high purity, installation of expensive manufacturing facilities and provision of storage containers capable of withstanding very low temperatures. Thus, this method has found utility in only limited applications.
The method (C) makes use of the ability of a certain metal or alloy to occlude hydrogen and convert itself into a metal hydride and the ability of this metal hydride to release the hydrogen and convert itself back to its original metal or alloy. It enjoys better practical utility than the methods (A) and (B). Research has been positively pursued in search of alloys which are optimum for the storage of hydrogen by occlusion. On the other hand, almost no consideration has been given to the development of a device for storage of hydrogen by use of such an alloy. The development of such a device has been generally ignored because of a very great difficulty which soon becomes obvious to anyone who begins developmental work. Alloys for storing hydrogen evolve heat during the occlusion of hydrogen and absorb heat during the release of hydrogen. This means that the storage device must be of a structure which allows the evolution and absorption of heat to proceed smoothly. To devise a device of a structure which permits smooth evolution and absorption of heat is a very difficult task.
The inventors therefore continued a diligent study in search of a device with a construction which is free from the aforementioned problem of heat conduction involved during the occlusion and release of hydrogen by the alloy and capable of retaining, in principle, the optimum charge amount of the alloy for the storage of hydrogen. The present invention has resulted from this study.
The object of this invention is to provide a device for the storage of hydrogen by use of an alloy capable of occluding hydrogen, which device eliminates the problem of heat conduction involved during the occlusion and release of hydrogen by the alloy, enjoys high operational efficiency and economy, has high safety, and permits ready scaling up of the equipment for large applications.